Locking coupling connector

ABSTRACT

A locking coupling comprises a body (1) adapted for connection to a separate body, a coupling collar (2) rotatably mounted on said body (1) and adapted to cooperate with said separate body to hold it in axial connection with said body (1), a locking collar (4) mounted on said body (1) and longitudinally movable thereon between locking and unlocking position, bias means (8) that urges the locking collar (4) towards the locking position, and locking formations (11, 10) on the locking collar (4) and coupling collar (2) that interengage axially when the locking collar (4) is moved to the locking position so as to restrain the coupling collar (2) against rotation on said body (1). The locking collar (4) can be retained in the unlocking position by retention formations (5, 9) on the locking collar (4) and body (1) that interengage longitudinally. The locking collar (4) is held captive longitudinally on the body by The coupling collar, and the latter is held captive on the body by an internal circlip (3). The locking formations (10, 11) comprise axially extending teeth of a saw-tooth form. Warning indicator means on said body (1) is exposed only when the locking collar (4) is in the unlocking position.

This invention relates to a locking coupling, especially vibrationresistant locking couplings suitable for use with electrical, pneumatic,hydraulic or optical couplings.

It is common practice to connect multiple electrical conductors togethersimultaneously with a two-part electrical coupling comprising a pair ofelectrical connectors in which the conductors terminate and which arepushed together and held together longitudinally by a coupling nut onone connector which engages a thread on the other. A harness assembly inthe form of a protective sleeve may cover the conductors and beconnected to the electrical connector at one end. It is also known toprovide such electrical couplings with a backshell assembly whichprovides a transition between the conductors usually within a harnessassembly, and the electrical connector in which they terminate. Abackshell assembly is typically tubular in construction and is attachedto the rear of the connector by a coupling nut. The rear end of thebackshell assembly may also carry a fitting, such as a coupling nut, forengagement with other components of the harness assembly, such as acable clamp.

Where electrical couplings and backshell assemblies are subjected toshock or vibration in use, there is the risk that coupling nuts may workloose, and for this reason some form of locking means is sometimesprovided to prevent counter-rotation of the coupling nut once it hasbeen tightened up. Many different forms of locking means have beenproposed, but these can be complicated to manufacture, assemble and use.

An object of the present invention is to provide a locking coupling withimproved locking means.

According to the present invention, a locking coupling comprises a bodyadapted for connection to a separate body, a coupling collar rotatablymounted on said body and adapted to cooperate with said separate body tohold it in axial connection with said body, a locking collar mounted onsaid body and longitudinally movable thereon between locking andunlocking position, bias means that urges the locking collar towards thelocking position, and locking formations on the locking collar andcoupling collar that interengage axially when the locking collar ismoved to the locking position so as to restrain the coupling collaragainst rotation on said body.

Preferably, the locking collar can be retained in the unlocking positionby retention formations on the locking collar and body that interengagelongitudinally. For example, the retention formations may comprisekeying means that guide the locking collar longitudinally on the bodyand allow rotation of the locking collar on the body only in theunlocking position, when the keying means then cooperate longitudinallyto retain the locking collar in the unlocking position.

Preferably, the locking collar is held captive longitudinally on thebody by the coupling collar, and the coupling collar in turn is heldcaptive on the body by a separate fastener such as an internal circlip.

Preferably, the locking formations comprise axially extending teethwhich may have a saw-tooth form so as to restrain the coupling collaragainst rotation in one sense which would otherwise allow uncoupling ofsaid separate body. The teeth comprise a long sloping side and a shortside which is substantially parallel with the longitudinal axis of theconnector. The short side may be undercut (i.e. inclined in the samesense as the long sloping side) to enhance the locking action of thecoupling.

An additional preferred feature of the invention comprises indicatormeans on said body which is covered by the locking collar and onlyexposed as a warning when the locking collar is in the unlockingposition.

The invention will now be described by way of example with reference tothe accompanying drawings in which:

FIG. 1 is a part side elevation and part axial section of a lockingcoupling according to the invention with the locking collar in thelocking position;

FIG. 2 is an enlargement of part of the drawing of FIG. 1;

FIG. 3 is a similar view to that of FIG. 1, except that it shows thelocking collar in the unlocking position;

FIG. 4 is an end elevation of the body of the locking coupling of FIG.1; and

FIG. 5 is a view of the locking collar of the locking coupling of FIG. 3on the line S--S.

The illustrated embodiment comprises a tubular body 1. which may be abackshell adaptor to support a bundle of electrical cables that enter itfrom the rear and terminate in an electrical connector supported withinthe front end of the backshell. A coupling nut 2 is rotatably mounted onthe front end of the body 1 and is held captive longitudinally thereonby a circlip 3 engaging respective annular grooves in the cooperatingsurfaces of the nut and body. The nut 2 projects longitudinally beyondthe end of the body 1 and is threaded internally for engagement with theaforesaid electrical connector when in use.

Adjacent to the rear of the coupling nut 2, a locking ring or collar 4is mounted on the body 1, and is formed with a set of inwardlyprojecting lugs 5 which engage respective longitudinally extendinggrooves 6 in an annular collar 9 formed on the outer surface of the bodyso as to guide the locking ring, 4 longitudinally over a short sectionof its length between the rear face of the nut 2 and an outwardlyprojecting annular flange 7 around the periphery of the body 1. A springwasher 8 is located between the flange 7 and rear face of the lockingring 4 and acts to urge the latter to a locking position in engagementwith the rear face of the coupling nut 2, as shown in FIG. 1.

The rear annular face of the coupling nut 2 is formed with teeth 10 thatproject longitudinally of the body 1 towards the locking ring 4, and theadjacent annular face of the locking ring 4 is formed with teeth 11 thatproject longitudinally of the body 1 towards the coupling nut 2 so as tocooperate with the teeth 10 on the latter. These teeth 10 and 11 run ina saw-tooth form around the full annular length of the faces, respectivewith corresponding alternating inclined and circumferentially abuttingedges so that the teeth can ride over one another with a ratchet actionwhen the nut 2 is rotated in one sense to secure an electrical connectorto the body 1, and lock together circumferentially to prevent rotationof the nut 2 in the opposite sense that would release said electricalconnector. Thus, it is only when the locking ring 4 is movedlongitudinally against the action of the spring washer 8 to disengagethe teeth 10,11 that the coupling nut 2 can be rotated to release saidelectrical connector. Furthermore, the arrangement of the teeth 10,11 issuch that an interengaging locking action is maintained even if thelocking ring 4 is tilted accidentally on the body 1, the teeth 10,11disengaging on one side of the body, but remaining in engagement on theother of the body.

In order that the locking ring 4 can be retained in a longitudinalunlocking position spaced away from the coupling nut 2, the inwardlyprojecting lugs 5 and collar 9 are dimensioned longitudinally so thatthe lugs 5 disengage the grooves 6 and are located in the annular groove12 between the flange 7 and collar 9, as shown in FIG. 3, whereupon thering 4 can be rotated to a position in which the lugs 5 are out ofalignment with the grooves 6. The ring 4 can then be released and willbe retained longitudinally by engagement of the lugs 5 with the adjacentside wall of the collar 9 through the spring action of the washer 8.Further rotation of the locking ring 4 whilst spring-loaded against theside wall of the collar will release the ring from the unlockingposition when the lugs 5 again come into alignment with the grooves 6,the ring 4 then being free to move longitudinally. Annular recesses 14and 15 are provided in the adjacent faces of the flange 7 and lockingring 4 to accommodate the spring washer 8 when the locking ring is inthe unlocking position.

The groove 12 to the rear of the collar 9 is coloured green or blue soas to indicate when the locking ring 4 is in the locking position, and ashallow groove 13 forward of the collar 9 is coloured red so that it isclearly visible when the locking ring is in the unlocking position, andthereby serving as a warning that the coupling nut 2 is not locked.

The outer circumferential surfaces of the coupling nut 2 and lockingring 4 are each textured to assist gripping and rotation, this beingespecially important in oily environments. Also, the texturing used,whether knurling or ribs, are preferably different in each case toassist tactile differentiation between the two components in question.

The outer diameters of the coupling nut 2 and locking ring 4 arepreferably different so as to assist selective operation of one or theother and avoid accidental operation of either member. For example,accidental rotation of the locking ring 4 by a tool engaging thecoupling nut 2 could damage the lugs 5 of the former so that it is nolonger effective. This can be avoided by making the locking ring 4 ofsmaller diameter than the coupling nut 2, as shown in the drawings, butequally the locking ring 4 could be made significantly larger indiameter to avoid the same problem.

In some applications, a special tool might be provided to operate thelocking ring.

The number of teeth can be freely chosen to select the amount ofrotation that separates each locking position. It has been found that aresolution of 10° or so between each locking position maintains goodelectrical connection between the opposing parts of the coupling. Thisrequires the provision of 30 or more teeth on the nut and locking ring.

Drain holes may be provided in the region of the spring washer 8 toallow the escape of moisture due to condensation.

In a further arrangement the short faces of the teeth may be inclinedwith respect to the longitudinal axis of the connector by betweensubstantially 0 and 5° in an undercut manner to further enhance theresistance of the locking ring to unintentional disengagement due toextreme vibration.

We claim:
 1. A locking coupling comprising: a body (1) adapted forconnection to a separate body; a coupling collar (2) rotatably mountedon said body and adapted to cooperate with said separate body to hold itin axial connection with said body, said coupling collar being rotatablein a locking sense to hold said body (1) and said separate bodytogether, and in a release sense to release said body from said separatebody; a locking collar mounted on said body and longitudinally movablewith respect to the coupling collar between locking and unlockingpositions; bias means (8) that urge the locking collar (4) towards thelocking position; and locking formations (10, 11) on the locking collarand coupling collar; characterised in that the locking collar (4) isrestrained from rotating when it is at the locking position and in thatthe locking formations on the coupling collar interengage axially withthose on the locking collar when the locking collar is moved to thelocking position so as to restrain the coupling collar against rotationin the release sense on said body (1).
 2. A locking coupling as claimedin claim 1 in which the locking collar (2) is retained in the unlockingposition by retention formations (5,9) on the locking collar and bodythat interengage longitudinally.
 3. A locking coupling as claimed inclaim 2 in which the retention formations comprise keying means thatguide the locking collar longitudinally on the body and allow rotationof the locking collar on the body only in the unlocking position, whenthe keying means then cooperate longitudinally to retain the lockingcollar in the unlocking position.
 4. A locking coupling as claimed inany one of the preceding claims in which the locking collar (4) is heldcaptive longitudinally on the body by the coupling collar (2), and thecoupling collar in turn is held captive on the body by a separatefastener (3).
 5. A locking coupling as claimed in claim 4 in which theseparate fastener (3) comprises an internal circlip.
 6. A lockingcoupling as claimed in any one of the preceding claims in which thelocking formations comprise axially extending teeth (10,11).
 7. Alocking coupling as claimed in claim 6 in which the teeth have a toothform so as to restrain the coupling collar against rotation in one sensewhich would otherwise allow uncoupling of said separate body.
 8. Alocking coupling as claimed in any one of the preceding claims in whichindicator means on said body is covered by the locking collar and onlyexposed as a warning when the locking collar is in the unlockingposition.